Compressed gas-powered projectile accelerators have been used extensively to propel a wide variety of projectiles. Typical applications include weaponry, hunting, target shooting, and recreational (non-lethal) combat. In recent years, a large degree of development and invention has centered around recreational combat, where air-guns are employed to launch non-lethal projectiles which simply mark, rather than significantly injure or damage the target. Between launching projectiles such air-guns are generally loaded and reset to fire when the trigger is pulled, generally referred to as “re-cocking” either by an additional manual action by the operator, or pneumatically, as part of each projectile-accelerating event or “cycle”. These devices may be divided into two categories—those that are “non-regulated” or “inertially-regulated”, and those that are “statically-regulated”.
Non-regulated or inertially-regulated air-guns direct gas from a single storage reservoir, or set of reservoirs that are continuously connected without provision to maintain a static (zero-gas flow) pressure differential between them, to accelerate a projectile through and out of a tube or “barrel”. The projectile velocity is typically controlled by mechanically or pneumatically controlling the open time of a valve isolating the source gas, which is determined by the inertia and typically spring force exerted on moving parts. Examples of manually re-cocked non-regulated or inertially-regulated projectile accelerators are the inventions of Perrone, U.S. Pat. No. 5,078,118; and Tippmann, U.S. Pat. No. 5,383,442. Examples of pneumatically recocked non-regulated or inertially-regulated projectile accelerators (this type of projectile accelerator being the most commonly used in recreational combat) are the inventions of Tippman, U.S. Pat. No. 4,819,609; Sullivan, U.S. Pat. No. 5,257,614; Perrone, U.S. Pat. Nos. 5,349,939 and 5,634,456; and Dobbins et al., U.S. Pat. No. 5,497,758.
Statically-regulated air-guns transfer gas from a storage reservoir to an intermediate reservoir, through a valve which regulates pressure within the intermediate reservoir to a controlled design level, or “set pressure”, providing sufficient gas remains within the storage reservoir with pressure in excess of the intermediate reservoir set pressure. This type of air-gun directs the controlled quantity of gas within said intermediate reservoir in such a way as to accelerate a projectile through and out of a barrel. Thus, for purposes of discussion, the operating sequence or “projectile accelerating cycle” or “cycle” can be divided into a first step where said intermediate reservoir automatically fills to the set pressure, and a second step, initiated by the operator, where the gas from said intermediate reservoir is directed to accelerate a projectile. The projectile velocity is typically controlled by controlling the intermediate reservoir set pressure. Examples of statically regulated projectile accelerators are the inventions of Milliman, U.S. Pat. No. 4,616,622; Kotsiopoulos, U.S. Pat. No. 5,264,778; and Lukas et al., U.S. Pat. No. 5,613,483.
More recently, electronics have been employed in both non-regulated and statically-regulated air-guns to control actuation, timing and projectile velocity. Examples of electronic projectile accelerators are the inventions of Rice et al., U.S. Pat. No. 6,003,504; and Lotuaco, III, U.S. Pat. No. 6,065,460.
Problems with compressed gas powered guns known to be in the art, relating to maintenance, complexity, and reliability, are illustrated by the following partial list:
Sensitivity to liquid CO2—The most common gas employed by air-guns is CO2, which is typically stored in a mixed gas/liquid state. However, inadvertent feed of liquid CO2 into the air-gun commonly causes malfunction in both non-regulated or inertially regulated air-guns and, particularly, statically-regulated air-guns, due to adverse effects of liquid CO2 on valve and regulator seat materials. Cold weather exacerbates this problem, in that the saturated vapor pressure of CO2 is lower at reduced temperatures, necessitating higher gas volume flows. Additionally, the dependency of the saturated vapor pressure of CO2 on temperature results in the need for non-regulated or inertially regulated air-guns to be adjusted to compensate for changes in the temperature of the source gas, which would otherwise alter the velocity to which projectiles are accelerated.
Difficulty of disassembly—In many air-guns known to be in the art, interaction of the bolt with other mechanical components of the device complicates removal of the bolt, which is commonly required as part of cleaning and routine maintenance.
Double feeding—air-guns known to be in the art typically hold a projectile at the rear of the barrel between projectile accelerating cycles. In cases where the projectile is round, a special provision is required to prevent the projectile from prematurely rolling down the barrel. Typically, a lightly spring biased retention device is situated so as to obstruct passage of the projectile unless the projectile is thrust with enough force to overcome the spring bias and push the retention device out of the path of the projectile for sufficient duration for the projectile to pass. Alternatively, in some cases close tolerance fits between the projectile caliber and barrel bore are employed to frictionally prevent premature forward motion of the projectile. However, rapid acceleration of the air-gun associated with movement of the operator is often of sufficient force to overcome the spring bias of retention device, allowing the projectile to move forward, in turn allowing a second projectile to enter the barrel. When the air-gun is subsequently operated, either both projectiles are accelerated, but to lower velocity than would be for a single projectile, or, for fragile projectiles, one or both of the projectiles will fracture within the barrel.
Bleed up of pressure—Statically-regulated air-guns require a regulated seal between the source reservoir and intermediate reservoir which closes communication of gas between said reservoirs when the set pressure is reached. Because this typically leads to small closing force margins on the sealing surface, said seal commonly slowly leaks, causing the pressure within the intermediate reservoir to slowly increase or “bleed up” beyond the intended set pressure. When the air-gun is actuated, this causes the projectile to be accelerated to higher than the intended speed, which, with respect to recreational combat, endangers players.
Not practical for fully-automatic operation—Air-guns which have an automatic re-cock mechanism can potentially be designed so as accelerate a single projectile per actuation of the trigger, known as “semi-automatic” operation, or so that multiple projectiles are fired in succession when the trigger is actuated, known as “fully-automatic” operation. (Typically air-guns that are designed for fully-automatic operation are designed such that semi-automatic operation is also possible.) Most air-guns known to be in the art are conceptually unsuitable for fully-automatic operation in that there is no automated provision for the timing between cycles required for the feed of a new projectile into the barrel, this function being dependent upon the inability of the operator to actuate the trigger in excess of the rate at which new projectiles enter the barrel when operated semi-automatically. Air-guns known to be in the art which are capable of fully-automatic operation typically accommodate this timing either by inertial means, using the mass-induced resistance to motion of moving components, or by electronic means, where timing is accomplished by electric actuators operated by a control circuit, both methods adding considerable complexity.
Difficult manufacturability—Many air-guns known to be in the art, particularly those designed for fully automatic operation, are complex, requiring a large number of parts and typically the addition of electronic components.
Stiff or operator sensitive trigger pull—The trigger action of many non-electronic air-guns known to be in the art initiates the projectile accelerating cycle by releasing a latch obstructing the motion of a spring biased component. In many cases, since the spring bias must be quite strong to properly govern the projectile acceleration, the friction associated with the release of this latch results in an undesirably stiff trigger action. Additionally, this high friction contact results in wear of rubbing surfaces. Alternatively, in some cases, to reduce mechanical complexity and circumvent this problem, the trigger is designed such that its correct function is dependent upon the technique applied by the operator, resulting in malfunction if the operator only partially pulls the trigger through a minimum stroke.
High wear on striking parts—In many air-guns known to be in the art, particularly those designed for semi-automatic or fully-automatic operation, the travel of some of the moving parts is limited by relatively hard impact with a bumper. Additionally, in many cases, a valve is actuated by relatively hard impact from a slider. The components into which the impact energy is dissipated exhibit increased rates of wear. Further, wear of high impact surfaces in the conceptual design of many air-guns known to be in the art make them particularly un-adaptable to fully-automatic operation.
Contamination—Many of the air-guns known to be in the art require a perforation in the housing to accommodate the attachment of a lever or knob to allow the operator to perform a necessary manipulation of the internal components into a ready-to-fire configuration, generally known as “cocking”. This perforation represents an entry point for dust, debris, and other contamination, which may interfere with operation.
In another aspect of the present invention, in lieu of direct connection of the valve passage and the chamber, the valve and chamber can be connected indirectly by being both connected to a distribution bus, or gas distribution passage, parallel to the bolt bore and valve passage, which simultaneous allows much greater flexibility of the overall configuration while providing a simple means of distributing gas to other functions such as allowing a simple interface with a passage directing gas to a jet that assists in the introduction of projectiles into the barrel. Additionally, this gas distribution passage provides a simple means of controlling flow to the jet by facilitating the incorporation of a throttling screw at the intersection with the passage communicating gas to the jet.
In another embodiment of the present invention, a valve locking feature is provided, whereby force is applied to hold the valve open during the filling of the intermediate reservoir, and then releases the valve body thereafter, reducing the amount of gas pressure required to hold the valve closed during completion of the projectile acceleration cycle. Additionally, because the valve opening force is supplemented by the locking force, the valve spring can be of light design, resulting in an ultra-light trigger pull. In addition, the valve slider diameter can be increased without increasing the spring force acting on the valve slider (with which, through friction, the trigger force scales), thereby allowing the use of larger, more robust seals. Both pneumatic and mechanical techniques to accomplish valve locking are herein described, which can be implemented individually or in combination.
It is desirable in many applications to minimize the length of projectile accelerator barrels. In another embodiment of the present invention, the bolt and breech are designed to allow the replacement a bumper with a stationary (not moving with the bolt) combined bumper and seal, thereby eliminating the need for the front bolt seal and allowing the shortening of the bolt and passage in which it slides, and thereby the overall device, by the length along which the seal slides. When not in operation, with no pressure applied within the chamber formed ahead of the step in the bolt diameter and corresponding step in the breech bore, the pressure of the bolt resting against the combined seal and bumper under the force of the bolt spring will maintain a ready seal between the bolt and breech, which will be sustained during operation as the pressure applied by the bolt is replaced by gas pressure, as the bolt moves rearward, sliding within the combined bumper and seal.
In many applications it is desirable for the first projectile to be fired as quickly as possible following a pull of the trigger, to minimize time for accidental perturbation of aiming and movement of the target during the time for the compressed gas-powered projectile accelerator action to be complete. Thus, it will be advantageous to have the capability to adjust the first cycle to be faster than subsequent cycles. A method to accomplish these is herein detailed, where a second throttling point at the upstream end of a chamber, in turn upstream of the flow control throttling screw, can be used to allow gas accumulated between cycles within the chamber to fill the intermediate chamber faster on the first cycle than subsequent cycles.
The present application provides several methods for the incorporation of a cocking mechanism into the compressed gas-powered projectile accelerator described therein. A novel approach, described herein, embodies a complete cocking system within a plug closing the rear of the valve bore, thereby allowing the cocking capability to contained as a discreet, self-contained module. Further, one embodiment disclosed herein comprises a single piece valve slider comprising of a rear section incorporating the gas seals of the valve and a front portion providing an open cavity partially containing the valve spring and a step by which the sear can latch the valve slider in a non-operating position between cycle. A modification to the valve to include a counter spring can, however, allow the valve slider to be divided into two separate pieces, one acting solely as a valve, and the other containing the velocity control spring and interacting with the sear. So doing simplifies manufacture, and allows the valve to be constructed as a separate module from the remainder of the housing, which is advantageous in allowing a wider range of materials (some of which being unsuitable for use on a larger section of the housing due to weight, but having desirable qualities for use on the valve housing).
One embodiment disclosed herein describes a “dynamically-regulated” compressed gas-powered projectile accelerator which fills an intermediate reservoir as an integral part of, and at the beginning of, each projectile accelerating cycle. The cycle is initiated by the operator, preferably by the action of a trigger, which causes the filling of the intermediate reservoir by compressed gas. The second step of the cycle where the projectile is accelerated is then automatically activated when the pressure reaches a design threshold. In so doing, the filling of the intermediate reservoir may be used not only to regulate the projectile velocity, but the time of each cycle, providing numerous advantages.
In one embodiment, a gas communicated into a chamber that applies pressure to the valve body (therein denoted the “valve slider”) closes the valve when a design pressure reaches a sufficient level to overcome a spring biasing the valve to open. During venting of the gas into the barrel to accelerate the projectile, however, the device relies partially on the bolt inertia and pressure drop through the gas flow path into the barrel (through a hole or slot connecting to the breech and through the hollow bolt) to hold the valve closed until the firing cycle is complete, and an optional throttling screw is described to enable tuning of a flow restriction governing this pressure drop. This causes some loss of efficiency, in preventing full use of the gas to accelerate the projectile. While use of a stiff bolt spring can minimize the dependence upon the bolt inertia and flow frictional losses to hold the valve closed during venting, the added loading subjects adjoining components to additional wear.
Alternatively, dependence upon the bolt inertia and flow losses to hold the valve closed during venting can be avoided by the addition of a valve locking feature, which first applies force to hold the valve open during the filling of the intermediate reservoir, and then releases the valve body thereafter, reducing the amount of gas pressure required to hold the valve closed during completion of the projectile acceleration cycle. Additionally, because the valve opening force is now supplemented by the locking force, the valve spring can be of arbitrarily low stiffness, resulting in an ultra-light trigger pull. Further, the valve slider diameter can be increased without increasing the spring force acting on the valve slider (with which, through friction, the trigger force scales), thereby allowing the use of larger, more robust seals. Both pneumatic and mechanical techniques to accomplish valve locking are herein described, implementable individually or in combination.
In many applications it is desirable for the first projectile to be fired as quickly as possible following a pull of the trigger, to minimize time for accidental perturbation of aiming and movement of the target during the time for the compressed gas-powered projectile accelerator action to complete. A means for adjusting the cycle to a relatively slow rate, and, for adjusting the first cycle to be faster than subsequent cycles is herein detailed, where a second throttling point at the upstream end of a chamber, in turn upstream of the flow control throttling screw of the compressed gas-powered projectile accelerator, can be used to allow gas accumulated between cycles within the chamber to fill the intermediate chamber faster on the first cycle than subsequent cycles.
A unique cocking means is disclosed herein, embodying a complete cocking system within a plug closing the rear of the valve bore, thereby allowing the cocking capability to be added or removed as a discreet, self contained module.